It didn't take much for Ryan Reynolds to convince Brad Pitt to make a cameo in Deadpool 2.

He just asked over a cup of coffee.

The 41-year-old actor, along with the cast and crew of the hit meta-superhero franchise, spoke with ET's Kevin Frazier on Saturday at Comic-Con in San Diego, California, about the film and its numerous cameos. Perhaps the most surprising appearance (spoiler alert) in the sequel was a Deadpool ally known as The Vanisher.

The Vanisher was, naturally, invisible the entire film -- except for a split second shot where he is revealed to be none other than Brad Pitt. "Brad Pitt said he'd do it if Ryan personally delivered a cup of coffee from Starbucks, right?" asked Deadpool 2 co-writer, Rhett Reese.

"Sort of embellished," Reynolds responded. "I was told all he wants is a cup of coffee and I said, 'Like a franchise or just one individual cup of coffee?' And I was told one individual cup of coffee, which was really his way of saying, 'I'm doing it for nothing.' And it was a total solid and the nicest thing anyone could do."

"I just loved it, because what's more irresponsible than taking one of the biggest movie stars in the world and giving him a role that is utterly wordless and invisible with an exception of three frames of film?" Reynolds continued. "Yeah, that’s kind of amazing."

The entire franchise is an unusual one, with the titular character routinely lampooning typical superhero tropes and frequently breaking the fourth wall to directly address the audience. Its uniqueness -- and success -- is likely the only reason such a cameo could occur, said Deadpool 2 director, David Leitch.

"I knew both of those guys and I worked with them before, but they would have never done a cameo in a movie I directed if it wasn’t Deadpool," Leitch told ET. "There’s such a... beloved feeling for the things you guys created in the first one that it was an easy ask."

The Deadpool 2 Super Duper $@%!#& Cut, from Twentieth Century Fox Home Entertainment,arrives Aug. 7 on digital as well as on 4K Ultra HD and Blu-ray on Aug. 21.